Waveguides are commonly used for transmitting electromagnetic wave energy from one point to another and are known in the art. A common use for waveguides is in the transmission of electromagnetic signals between an antenna and transmitting or receiving equipment. Waveguides are also used more generally in the connecting together of transmitting and receiving equipment. The present invention relates to a waveguide adaptor assembly and to a waveguide assembly for connecting waveguides. It will be appreciated that there are many further uses of waveguides falling within the scope of the invention.
A waveguide typically comprises a transmission line formed from a hollow conducting tube providing a conduit through which electromagnetic waves are propagated. The tube is typically of constant cross-section throughout the length of propagation and may be of a flexible or rigid type. Common cross-sectional shapes for the conduits of such waveguides include, for example, square, rectangular, circular, or elliptical.
As noted above, it is generally necessary for waveguides to be coupled or connected to transmitting or receiving equipment, or an antenna. To this end, waveguides are commonly fitted with a coupling system for use therewith. It is widely known that both the design of the waveguide and the coupling system are critical to the overall performance of the assembly. In order to reduce reflection losses and impedance mismatches, waveguides are often mounted to an interface, such as a waveguide flange connector.
Specifications for standard interfaces, such as waveguide flange connectors, vary from one application to another, and are largely determined by each manufacturer's transmitting or receiving equipment requirements. On the other hand, waveguides themselves are typically of standard dimensions, sizes of which are well-known in the art.
Many flange connectors incorporate a gasket between the mating face of the flange and the apparatus or equipment to which the waveguide is being connected. To prevent the ingress of water, in particular for assemblies intended for outdoor applications, a sealing groove may be provided in the flange surface, such that a gasket may be seated in the groove.
A common method of connecting a waveguide to an interface, such as a waveguide flange connector, involves the use of molten solder to form a joint between the waveguide and the connector. Solder between the waveguide and flange connector creates an electrically uniform and secure connection and allows for waveguide flange connectors to be pre-installed on the waveguide before the complete waveguide assembly is shipped, ready for use.
An alternative manner of connecting a waveguide is disclosed in US 2005/0285702. The method comprises fitting a flange adapter to the end of a waveguide, such that it is securely fastened. An interface is provided, the interface having a retaining groove, a side of which is to integrate with the flange adapter. During construction, the flange adapter comprising the waveguide is inserted into the interface retaining groove, and a retainer inserted, which biases the interface end of the flange adapter against the interface, thus clamping together the respective parts.
An alternative approach to the above is provided in US 2003/0137465. The method again comprises the use of a flange adapter for coupling to a waveguide. An interface is provided, the interface having a semi-permanent coupling means. The flange adapter is secured to the coupling means by a bolted arrangement, thus allowing multiple interfaces to be interchanged between the same waveguide.
Similar approaches for connecting waveguides to that disclosed in US 2003/0137465 are disclosed in GB 1,135,258 and GB 1,131,826. GB 1,135,258 discloses a method of attaching a waveguide to a flange. In this case, there is provided a flange and coupling assembly comprising a clamping arrangement including a flange member and a clamping member, both of which have a rectangular opening therethrough. A waveguide is first inserted through the clamping member so as to extend through fully in an opposing direction to the flange member. Four clamping surfaces are formed by deforming the side walls of the waveguide, and the clamping member brought into contact with the flange. A bolted arrangement securely fastens the two sections together.
GB 1,131,826 discloses another method for securing a waveguide to a flange. A coupling arrangement is provided for connecting together two tubular members on a common axis. Both the waveguide and flange are provided with locking means, including a rigid lug and a deformable lug, and arranged such that the deformable lug is able to be bent around the rigid lug, so as to lock the waveguide to the flange.
Yet a further alternative approach is disclosed in US 2007/0262837. The document is concerned with providing a waveguide with a waveguide interface, the waveguide interface comprising a split ring with a first half and a second half joined by a web portion. Both portions of the split ring are configured to mate with the waveguide, which, during assembly, are provided to clamp the exterior of the waveguide and communicate with an overbody. The overbody is drawn against the split ring, which seats the split ring within the overbody. The overbody comprising the split ring and waveguide are then secured to an interface element by way of bolted fasteners. The complete assembly may then be aligned and fitted to engage any number of corresponding interfaces.
A particular issue arising with connector assemblies for waveguides is the occurrence of corrosion, in particular galvanic corrosion arising at the joint between two dissimilar metals. Techniques are known in the art for reducing galvanic corrosion. For example, it is known to coat the mating faces of the parts of the joint with a layer of a metal, in particular silver or tin. However, this measure is costly and time consuming.
There is a need for an improved assembly for coupling a waveguide to an apparatus or item of equipment. It would be advantageous if the assembly could be inexpensive to manufacture. It would be further advantageous if the assembly could reduce or prevent the occurrence of corrosion, in particular galvanic corrosion, as occurs with known devices.